Health + Prevention

Glaucoma, cataract, AMD, etc.: eye diseases and how to catch them in time

Symptoms, causes and treatments at a glance

20 February 2022

The eye is our most important sensory organ – and it’s as complex as it is sensitive. Numerous eye diseases can have an impact on our vision – and dire consequences for the way we perceive the world around us. This includes everything from harmless eye diseases such as chronically dry eyes, vitreous opacities and squinting to cataract, glaucoma and macular degeneration. BETTER VISION explains: What are the most common eye diseases and how can you recognise them? Symptoms, causes, treatment and prevention – at a glance.

  • Lunch in the garden for multi-generation family


Handsome mature man outdoors
  • Apart from a glaucoma attack where the intraocular pressure suddenly rises very quickly, glaucoma is only noticeable once it has already caused considerable damage to the optic nerve and/or retina. Typical symptoms are teary eyes and visual impairments like a field of view that is arched and externally narrowed. This is the area you can see without moving your head. Sometimes it causes the centre of the visual field to fail, or coloured rings to appear when looking at bright light sources. With certain types of glaucoma, those affected experience a general loss of visual acuity and reduced contrast perception.

    Acute glaucoma or a glaucoma attack are when there is a strong, sudden build-up of pressure in the affected eye. This can be accompanied by symptoms like red and “hard” eyes, eye pain and headaches, nausea, vomiting and fixed pupils (when the pupil does not react to light) and by sudden loss of vision.

  • Glaucoma is an umbrella term for different types of the disease; the majority are characterised by increased intraocular pressure and/or a circulatory disorder affecting the optic nerve. In rarer cases, glaucoma also occurs at low intraocular pressure. Certain risk factors promote increased intraocular pressure, and as such the likelihood of contracting one of the various types of glaucoma. This includes diabetes mellitus, cardiovascular diseases, eye infections, myopia, numerous cortisone treatments, possible cases in the family and an age of over 65.

  • The type of glaucoma determines the treatment. Eye drops can often help reduce intraocular pressure. Alternatively, laser treatment or surgery can also achieve the desired results. Glaucoma surgery is usually performed under a local anaesthetic.

    Acute glaucoma is considered a medical emergency and must be treated immediately as it can otherwise lead to blindness. The patient is given medication to reduce the intraocular pressure before they undergo surgery.

  • Glaucoma cannot be prevented; only its risk factors can be influenced. Keeping diabetes mellitus and cardiovascular diseases such as high blood pressure at bay will help effectively reduce the risk of developing glaucoma.


Blurred image of business people walking

Typical symptoms are fading colours and contrasts

  • Depending on the stage of cataract, the symptoms can manifest to different degrees. Typical symptoms are fading colours and contrasts, trouble seeing at dusk or, in poor light, greater glare and reduced ability to adapt to light and darkness. Those affected experience serious restrictions on vision: spatially, in the near distance (e.g. when reading) and at a distance (e.g. when watching TV).

  • There are many causes of cataract. The most common is the natural aging process of the eye. Diabetes mellitus (type 1 and 2), skin diseases like neurodermatitis, tobacco consumption, eye injuries, medication (e.g. all types of cortisone), nutrient deficiency, chronic inflammation of the choroid and radiation (e.g.UV, X-ray or infrared) all promote cataract. Cataract can also be hereditary. In this case, it usually has non-hereditary factors, such as an infection with measles in the womb.

  • Cataract can only be properly treated through surgery. The cloudy lens is replaced by an artificial one (normally made of acrylic or silicone). The operation is normally performed as an outpatient procedure under local anaesthetic. The eye that is more affected is operated on first, and the other eye is normally treated a few days or weeks later – it all depends on the speed at which it heals.

  • Age-related cataract is a natural development and, as such, cannot be prevented. This is not the case if the cataract was caused by other factors. A link has been established between smoking and cataract – kicking the habit will therefore help prevent the disease. Key measures for preventing diabetes are a balanced diet, and getting enough sleep and regular exercise. The risk of damaging the eye, however, can be reduced by wearing goggles whenever you perform dangerous tasks (e.g. drilling or polishing). To avoid damage from UV rays, you should always wear glasses with the right coating; when on holiday or at the tanning studio, for example, opt for sunglasses, and ski goggles in the mountains.

Macular degeneration (AMD)

Distorted business people walking
  • Blue curved clinker texture

    A typical symptom of wet AMD is a restricted view of straight lines (e.g. frames or tile grooves), which appear bent.

    There are two types of macular degeneration: dry and wet. Dry macular degeneration is normally evident through reduced visual clarity in the central field of vision. When reading, the letters at the edge are clear, but those in the middle slightly blurred. Those affected often find it difficult to recognise faces. As macular degeneration progresses, vision becomes gradually worse until the central field of view is either considerably impaired or completely destroyed.

    Conversely, wet AMD is a result of dry macular degeneration. While rarer, its progression is much faster. It starts by causing drastic limitations in distance and near vision, and ultimately in an irreversible loss of sight. A typical symptom of wet AMD is a restricted view of straight lines (e.g. frames or tile grooves), which appear bent.

  • With dry macular degeneration, one part of the retina recedes, becomes thinner and dies. This destroys photoreceptor cells in the middle of the retina. With wet macular degeneration, new vessels grow from the choroid into the macula, where they result in bleeding and water retention.

  • While it’s not possible to cure macular degeneration, treatment can often slow or even stop disease progression.

    Conversely, macular degeneration can be treated in an outpatient procedure by injecting a certain medication into the eye (intravitreal injection), which the newly formed blood vessel pushes back, causing the macula to “dry out” once more. As this normally isn’t a permanent cure, the treatment must be repeated at regular intervals over a number of years.

  • As macular degeneration is one of the typical age-related eye diseases, people should go for regular retina check-ups once they reach 55. This means action can be taken to treat it early on.

Vitreous opacity

(mouches volantes, floaters or “flying flies”)

Vitreous opacity is noticeable through dark, often transparent dots, stripes or schlieren in the visual field.

Vitreous opacity is noticeable through dark, often transparent dots, stripes or schlieren in the visual field.

  • Vitreous opacity is noticeable through dark, often transparent dots, stripes or schlieren in the visual field – in particular against a bright background such as while reading or looking at the sky or snow. They appear to fly around but follow your eyes as they move. This phenomenon is also known as mouches volantes, or “flying flies.”

  • “Flying flies” is normally caused by the natural aging process of the vitreous body (corpus vitreum), which fills the majority of the eyeball. It comprises 98 percent water, and 2 percent protein components and connective tissue fibres. These components are normally dissolved in water and are thus invisible. Over time, the vitreous body shrinks and becomes liquefied. The collagen fibres clump together and suddenly appear cloudy. Vitreous opacity is a typical age-related eye disease. Roughly two thirds of 65- to 85-year-olds have such complaints, which affect short-sighted people earlier than either normal- or far-sighted people. Metabolic disorders such as diabetes mellitus, an injury or bruising of the eye, or taking certain medication can result in vitreous opacity.

  • Even if the “flying flies” are often considered irritating, in most cases they are harmless and don’t need to be treated. If the opacities limit vision and thus quality of life in a major way, there are treatment options out there. First there is vitreous removal (vitrectomy), whereby the vitreous body is removed either partially or completely, and the eye is filled with fluid or gas instead. Ophthalmologists don’t recommend this treatment due to the associated risk of blindness. A new and less-risky procedure is laser vitreolysis. This is a non-invasive procedure to treat vitreous opacities. Laser vitreolysis is performed as an outpatient procedure under local anaesthetic and is virtually painless: a laser is used to dissolve or crush the opacities of the vitreous body (photodisruption). Compared to vitreous removal, this treatment has far fewer risks and side-effects.

    The following exceptions call for urgent action: if the opacities suddenly get more intense and increase in number, or are accompanied by light flashes, this could indicate the early stages of retinal detachment. In this case, an ophthalmological examination should be performed immediately. The same applies if a rain of large black spots ensues: if patients suddenly see numerous dots that look like rain or billowing smoke in their field of vision, they could be experiencing vitreous haemorrhage that must be examined immediately by an ophthalmologist – possibly at a hospital. Please note that you will be unable to drive for several hours after being examined by an ophthalmologist because you will normally be given pupil-dilating eye drops.

  • A range of different factors influence eye health and thus the eye’s aging process. They include a balanced diet and a healthy lifestyle. Further, excessive pressure on the eyes should be avoided, such as strong rubbing.

Latent or hidden squinting


Double vision
  • Those affected often suffer from headaches, burning eyes or general overexertion of the eyes, which is often accompanied by exhaustion. Added to that are blurred vision, irritated eyes and double vision.

  • With latent squinting, the patient’s eyes are not completely parallel, which impairs their spatial vision. The brain and eye muscles keep trying to avoid double images, which can make patients very tired. A range of different factors impact the appearance of heterophoria: alcohol consumption, stress, fatigue and psychological strain. Many hours spent working at a computer can also promote heterophoria.

  • Latent squinting is usually a symptom of overexerting the eyes and often goes untreated. If it results in impairments, heterophoria can be corrected with a tailored pair of prism glasses. It balances out inconsistent perception thanks to a special polish in at least one of the lenses. This improves the mobility and interplay of the eyes, which permits more relaxed and better vision for the wearer.

  • While heterophoria cannot be prevented, measures can be taken to prevent any consequences, such as vision problems. But there are things you can do to avoid any consequences, such as visual impairment. Infants and small children should therefore regularly be checked so they can start receiving treatment as quickly as possible.

Manifest squinting

(heterophoria, strabismus concomitans)

smiling baby with eyeglasses
  • In most cases, manifest squinting affects babies and young children. With concomitant strabismus, the eyes can move in all directions but are still not focused on the same object. The squint angle is identical in all directions.

  • Concomitant strabismus is either inherited or brought on by long-sightedness. Other possible causes are visual impairment in one eye or restrictions on spatial perception.

  • Concomitant strabismus can be treated through occlusion therapy. The healthy eye is covered for anywhere from a few hours to several days to train the squinting eye to see properly. The visual centre thus receives the impulses it needs to be properly trained.

  • Concomitant strabismus cannot be prevented. But there are things you can do to avoid any consequences, such as visual impairment. Babies and young children should therefore be checked regularly in order to start a treatment early on if need be.

Paralytic strabismus

(strabismus paralyticus, strabismus incomitans)

Paralytic strabismus
  • With paralytic strabismus, one or several external eye muscles or a supplying nerve suddenly fails. All of a sudden, patients see double and complain about bad spatial perception, which is often accompanied by nausea, headaches and even dizziness. Patients may experience an oversensitivity to light, “shaky” or burning eyes and excessive blinking. The squint angle differs depending on the line of sight. People suffering from paralytic strabismus often compensate for this by tilting their head to relieve the paralysed muscle. In other words, they tilt their head until they can see straight.

  • Paralytic strabismus is usually brought on by an injury, a neurological disease, damage to a cranial nerve or an eye muscle inflammation. Circulatory disorders or tumours, for instance in the brain or eye sockets, can lead to paralytic strabismus.

  • Treatment for paralytic strabismus differs depending on the cause. One option is to correct the problem with a pair of prism glasses, which balance out inconsistent perception thanks to a special polishing technique applied to at least one of the lenses. Alternatively, the affected eye muscles can be operated on, and the neurotoxin botulinum can be administered as treatment. In some cases, paralytic strabismus cures itself after several weeks or months.

  • The prevention options depend on the cause of paralytic strabismus and are too different and diverse to explain in detail here. Your ophthalmologist will be happy to suggest a suitable diagnosis.


Sun corona on blue sky.

Patients at advanced stages of the disease complain of distorted vision or rings around bright light sources, shadow formation on objects, double vision, increased light sensitivity and limited vision at dusk or in the dark.

  • The cornea on both eyes becomes thinner and cone-shaped. Ongoing deformation will cause visual acuity to keep diminishing. This could indicate the beginning of a keratoconus if a patient’s prescription changes quickly over a short time. Both eyes will be affected, but not always to the same degree. The keratoconus can occur during childhood but most commonly manifests between the ages of 20 and 30. Disease progression also varies from one person to the next. Some people perceive keratoconus merely as a minor vision problem, while others need an operation. It’s usually no longer possible to wear contact lenses. Patients at advanced stages of the disease complain of distorted vision or rings around bright light sources, shadow formation on objects, double vision, increased light sensitivity and limited vision at dusk or in the dark.

  • There is not enough information on the causes and risk factors of keratoconus despite the many studies conducted. The suspected culprits include thyroid dysfunction or a genetic predisposition as keratoconus can occur multiple times in a single family. A high risk factor for keratoconus is strong and frequent rubbing of the eyes over a long period, for instance due to an allergy.

  • Treatment for keratoconus differs depending on the cause, but should be started as early as possible. If it turns out the thyroid gland is responsible, treatment with thyroid hormones may prove helpful. At a late stage, a corneal transplant is often the only option.

  • In all probability, keratoconus cannot be prevented as genetic factors would likely play a role in causing it. However, the risk factors can be minimized and, in the case of an allergy, patients should refrain from rubbing their eyes or take action to eliminate itchiness. This can involve desensitisation or taking the appropriate medication.

Eye diseases must be diagnosed and treated by an ophthalmologist. If you experience symptoms you aren’t able to assess, please consult your eye doctor immediately. If your eyes are healthy, an ophthalmologist can assess whether vision correction will improve your eyesight.

ZEISS Vision Care

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